Function Of Bulk Density Research Articles

How torrefaction impacts minimal fluidization velocity from different biomasses and their mixtures

Torrefaction has emerged as a promising technology for optimizing the efficiency of thermochemical processes. However, many challenges still need to be addressed regarding its integration with other processes, such as gasification. This work investigates the potential of torrefaction to transform the properties of biomass mixtures, improving operations in fluidized bed reactors. Experimentally, hazelnut shells and olive pit mixtures were torrefied at 280 °C for 45 min to analyze how torrefaction affected the minimum fluidization velocity as a bulk density function. The results were compared to other biomasses from the literature. Our findings show that torrefaction can stabilize minimum fluidization velocity at 0,45 m/s for mixtures of biomasses with bulk densities below 700 kg/m3 and particle size range (T) of 1,7 < T < 2,36 × 10−3 m. These findings collectively emphasize the potential of torrefaction as an effective technology for utilizing agro-industrial residues in energy generation processes not only for the improvement of conversion efficiency but also for operation stability.

The impacts of cover crop mixes on the penetration resistance model of an Oxisol under no-tillage

Soil penetration resistance is used as an indicator of mechanical resistance to root growth into the soil matrix. However, penetration resistance measured only under wet soil conditions may not identify the effects of cover crops on soil structure. We aimed to determine the impact of individual and mixes of cover crops on soil penetration resistance as a function of water content and bulk density in an Oxisol under no-tillage in southern Brazil. Six treatments of individual and mixed cover crops were tested: (i) black oat; (ii) ryegrass; (iii) forage radish; (iv) wheat; (v) Fibrous-rooted crop mix: with 80 % fibrous-rooted and 20 % tap-rooted plants; and (vi) Tap-rooted crop mix: 40 % fibrous-rooted and 60 % tap-rooted plants. Soil cores were collected from a depth of 0–0.10 and 0.10–0.20 m and soil penetration resistance was evaluated under four soil water matric potentials (−6, −33, −100, and −500 kPa). Soil penetration resistance (Q) data for each treatment were fitted as a function of bulk density (ρ) and water content (θ) [Q=f(ρ, θ)]. The soil penetration resistance model was a non-linear equation (i.e., a double power function, with a negative exponent for water content and a positive exponent for bulk density). Under a given combination of bulk density and water content values, soil penetration resistance was higher after single crops than crop mixes, indicating a crop-mediated soil strengthening process. The cover crop mixes increased the macroporosity, resulting in an adequate soil physical quality for successional crops such as soybean, although no differences were observed for cover crops at soil water matric potentials of −60 hPa and −330 hPa when soil penetration resistance was used as a static measurement. The modelling of the soil resistance to penetration, as a function of soil bulk density and soil water content, showed that cover crops changed soil cohesion and reduced the impact of drying on soil strength when compared to the single cropping systems, indicating that soil penetration resistance should be modelled under a broad range of water contents, instead of only under a specific soil water content, to quantify the impacts of cover crops on soil strength.

Surface morphology and dispersion interaction induced anomalous dynamics of solvation water of a hydrophobic fullerene molecule

Knowledge of accurate structural and dynamical features of the surrounding water of a C60 molecule is essential for the proposed uses of C60 in a wide variety of applications viz., in inhibiting HIV protease, DNA cleaving, macromolecular binding and drug delivery. Using molecular dynamics simulations, the present study demonstrates that the solute-water dispersion interaction induces anomalous bulk density dependence of dynamics of solvation water of the C60. In order to elucidate the origin of such behaviour, the analyses of the simulation trajectories are performed and it reveals the presence of two dynamically different types of water molecules: one (designated as Type 1 here), which has no radially outward movements (with respect to C60) throughout the simulation time and performs “bouncing ball” movements on the C60 surface by hopping from one face to another and the other one (Type 2) is fast and goes in and out of the solvation shell frequently. The anomalous dynamics is a consequence of the variable presence of such dynamically heterogeneous water molecules as a function of bulk density, and it, in turn, arises due to the interplay between two opposing effects emanating from the free volume (which depends on bulk density) and the inhomogeneous energy surface of the C60 arising due to icosahedral arrangement of carbon atoms on the surface and attractive solute-water dispersion interaction. It is to emphasize that model C60 with no attractive dispersion interaction does not show any anomalous dynamics.

Electrical conductivity of porous binary powder mixtures

Simultaneous data of the quasi-static compaction and electrical conductivity of porous, binary powder mixtures have been collected as a function of bulk density. The powder mixtures consist of a metal conductor, either titanium or iron, an insulator, and pores filled with ambient air. The data show a dependency of the conductivity in terms of relative bulk density and metal volume fraction on conductor type and conductor particle characteristics of size and shape. Finite element models using particle domains generated by discrete element method are used to simulate the bulk conductivity near its threshold while the general effective media equation is used to model the conductivity across the compression regime.

Predicting the Air Permeability of Ultrafine Glass Fiber Felts: A Comparison of Artificial Neural Network, Linear Fitting, and Polynomial Fitting

In this study, the air permeability of ultrafine glass fiber felts (UGFFs) as a function of bulk density and thickness was predicted by three analysis methods including linear fitting, polynomial fitting, and an artificial neural network (ANN). A 36-set database was obtained by the measurements of samples produced by the flame blowing process. It was shown that the ANN structure with six neurons in the hidden layer was optimal. The ANN model showed much better quality of predicting the permeation rate compared with linear fitting and polynomial fitting, which was evaluated by three important parameters, namely mean relative error (MRE), mean squared error (MSE), and correlation coefficient (R). The prediction diagrams applying the ANN model also matched the theoretical analysis very well, which verified the advantages and practicability of ANN.

Soil management and diverse crop rotation can mitigate early-stage no-till compaction and improve least limiting water range in a Ferralsol

No-till management systems tend to cause soil compaction in the early years of their establishment. Soil compaction reduces crop production due to restrictions on root development. Management strategies combining crop rotation and soil conservation practices still need to be researched as potential strategies to mitigate no-till soil physical constraints in tropical regions with prolonged drought periods and still promote agricultural sustainability. The objective of this study was to determine if soil specific management could mitigate early-stage no-till compaction and improve least limiting water range in a Rhodic Ferralsol. We hypothesized that no-till cropping systems with concomitant conservation practices –soil fertilization, crop rotation, and intercropped brachiaria grass– would improve soil physical quality (SPQ) and still achieve high crop yields in a tropical region with dry winters and frequent dry spells during wet season. Six no-till cropping systems were tested: soybean monoculture (T1); corn monoculture (T2); corn and soybean rotation (T3); corn and soybean rotation with intercropped brachiaria (T4); and two more with increased fertilization: corn and soybean rotation with intercropped brachiaria (T5), and corn and soybean rotation (T6). Least limiting water range (LLWR) was used as an indicator of SPQ. LLWR is computed as a function of bulk density (Bd), and it is defined as the range of soil water content in which physical constraints to plant growth are at minimal. Its critical limits are water contents associated with field capacity and air-filled porosity (upper limits), along with wilting point and soil resistance (lower limits). For each Bd, there is a LLWR value: the span between the upper limit and the lower limit. An adaptation of LLWR, in which we substituted the wilting point by the critical water content (θ*), was also tested (LLWR*). Critical Bd (BdC) value was 1.30 Mg m−3 for LLWR and LLWR*. In monoculture treatments (T1 and T2) the maximum Bd values exceeded the BdC (LLWR = LLWR * = 0) and negatively correlated with crop yield. Alternatively, cropping systems with diverse crop rotation (corn/soybean/brachiaria) showed greater values of LLWR and LLWR* and less soil compaction than monoculture systems. Usage of LLWR* evinced water stress was the main limiting plant growth factor; viz. θ* was more limiting than mechanical resistance and deficient aeration. These results support the hypothesis that the use of soil conservation practices and crop rotation during initial years of no-till farming contributes favorably to SPQ without compromising crop production.

Effect of Soil Compaction and Bulk Density on the Growth and Yield of Soybean (Glycine max) on Sandy Clay Loam Soil of the Semi-arid Region of Northern Nigeria as Influenced by Tractor Wheel Traffic

Soil compaction from farm machinery is an environmental problem. The effect of compaction on plant growth and yield depends on the crop grown and the environmental conditions that crop encounters. The effect of compaction from tractor traffic on soybean (Glycine max), variety TGX1448-2E, on a sandy clay loam soil in the semi-arid region of northern Nigeria was investigated for two growing seasons, 2015 and 2016. A randomized complete block design of the field of plots with treatments of 0,5,10, 15 and 20 passes of a tractor MF 390 was used. Each treatment was replicated three times. The soil bulk density, penetration resistance and soil moisture content for each applied load were measured and the yield from each treatment was determined. Agronomic treatments were kept the same for all plots in both 2015 and 2016. Results showed increased soil bulk density, penetration resistance and soil moisture content with increased tractor passes. Highest grain yield was obtained at 5 tractor passes with a mean bulk density of 1.76 Mgm,-3 penetration resistance 1.70 MPa and moisture content 13.37% with a mean yield of 2568 kgha-1 and lowest was obtained from 20 tractor passes were 340 kgha-1. Statistical models were used to predict yield as a function of bulk density, penetration resistance, moisture content, contact pressure, and a number of tractor traffic passes. Grain yield with respect to moisture content gave the best yield prediction (r2 = 0.94).

Study on the Critical Shear Stress of Cohesive Sediments

Since the measurements of bulk property parameters of cohesive sediments can be done easily, it is useful to relate the critical shear stress of cohesive sediments to some of these parameters. In this paper, data from two experiments are reanalysed and the dependence of the critical shear stress on bulk density, clay solid content and clay volume content is highlighted. The results from Sharif demonstrate the critical shear stress as a function of bulk density and clay solid content, while that from Kothyari and Jain indicate that the critical shear stress depends on both the clay solid content and clay volume content of cohesive sediments in the presence of gravel and air. Moreover, it is concluded a critical clay solid content exists around 18%, beyond which the critical shear stress increases rapidly with the increase of bulk density.

Thermal Properties of Raw Hemp Fiber as a Loose-Fill Insulation Material

ABSTRACTThe article presents the possibilities of using hemp fiber as a loose-fill insulation material. The article presents the results of research concerning raw hemp fiber obtained from the Polish crop of industrial hemp of Białobrzeskie variety. The analysis involved evaluation of thermal conductivity in function of bulk density and air permeability, the properties important for insulation materials. The results of laboratory investigation were used to create the numerical simulation models of heat transfer in the frame wall partitions filled with hemp fibers. The study showed that with the increase of bulk density, the thermal conductivity and air permeability of material decrease. The obtained lambda values are comparable with the characteristic values for conventional thermal insulation materials. The results of heat transfer and temperature distribution reveal that hemp fibers characterize with strongly air permeance, what affects on the need for additional barriers against air filtration.

Thermal conductivity of cement stabilized earth blocks

The present study examines the effect of bulk density and cement content on the thermal conductivity of cement stabilized earth blocks (CSEB). The experimental results show that the thermal conductivity increases as a function of bulk density; changes in cement content result in a small variation in thermal conductivity of CSEB at a given bulk density. No obvious linear relationship between the thermal conductivity and cement content of CSEB has been observed. However, a significant increase of compressive strength of CSEB caused by the addition of cement has been observed; moreover, the compressive strength of CSEB increases with increasing cement content. CSEB show potential in earth buildings due to their improved compressive strength and reduced thermal conductivity.

A density functional theory for colloids with two multiple bonding associating sites

Wertheim’s multi-density formalism is extended for patchy colloidal fluids with two multiple bonding patches. The theory is developed as a density functional theory to predict the properties of an associating inhomogeneous fluid. The equation of state developed for this fluid depends on the size of the patch, and includes formation of cyclic, branched and linear clusters of associated species. The theory predicts the density profile and the fractions of colloids in different bonding states versus the distance from one wall as a function of bulk density and temperature. The predictions from our theory are compared with previous results for a confined fluid with four single bonding association sites. Also, comparison between the present theory and Monte Carlo simulation indicates a good agreement.

Optimizing thermal and mechanical performance of compressed earth blocks (CEB)

Compressed earth blocks (CEB) were used for the construction, always and until now systematically with a bulk density of about 1800 and 2100kgm−3. These earth construction materials have a relatively high thermal conductivity of about 1.1Wm−1K−1. This study aims to obtain lightweight CEB by varying their bulk density in order to modify their porosity and consequently to act on their thermal conductivity. The approach adopted here involves an experimental study of the influence of compaction pressure on the bulk density of the compressed earth block (CEB) and its effects on their thermal performance (thermal conductivity and thermal effusivity) and mechanical properties (compressive strength and modulus of elasticity). Results show that bulk density has a strong influence on thermal and mechanical behavior of CEB. The decrease in the bulk density of CEB was accompanied by a significant reduction in their thermal conductivity and their thermal effusivity. This variation in thermal properties as a function of bulk density is performed linearly. However, the bulk density should not decrease under certain minimum values below which the CEB lose their cohesion and compressive strength.

Evaluation of physical properties of kidney beans (Phaseolus vulgaris)

The research work was conducted on the physical properties of three species of kidney bean (White speckled kidney bean, Red small kidney bean and Black kidney bean). Length, width, thickness varied between 1.04-1.7, 0.66-0.79, 0.49-0.58 cm for three species of kidney bean, respectively. Arithmetic mean diameter, geometric mean diameter, square mean diameter and equivalent diameter were 0.73-1.00, 0.70-0.96, 1.23-1.62, and 0.88-1.19 cm 2 , respectively. Sphericity and aspect ratio ranged between 0.56-0.67 and 0.45-0.64 for kidney bean, respectively. Porosity (%) as a function of bulk density and true density were 2.21-9.07(%), respectively. Volume, surface area and shape factor varied between 0.20-0.58, 1.53-3.47 and 0.88-1.015 cm, respectively. Thousand kernel mass (M 1000 ) were lowest for red small kidney bean (240 g) and highest for black kidney bean (499 g). The angle of repose of three varieties of kidney bean ranged between 21.74 to 23.79 0 .

Piezoelectric Ignition of Nanocomposite Energetic Materials

Piezoelectric initiators are a unique form of ignition for energetic material because the current and voltage are tied together by impact loading on the crystal. This study examines the ignition response of an energetic composite composed of aluminum and molybdenum trioxide nanopowders to the arc generated from a lead zirconate and lead titanate piezocrystal. The mechanical stimuli used to activate the piezocrystal varied to assess ignition voltage, power, and delay time of aluminum–molybdenum trioxide for a range of bulk powder densities. Results show a high dielectric strength leads to faster ignition times because of the higher voltage delivered to the energetic. Ignition delay is under 0.4 ms, which is faster than observed with thermal or shock ignition. Electric ignition of composite energetic materials is a strong function of interparticle connectivity, and thus the role of bulk density on electrostatic discharge ignition sensitivity is a focus of this study. Results show that the ignition delay times are dependent on the powder bulk density with an optimum bulk density of 50%. Packing fractions and electrical conductivity were analyzed and aid in explaining the resulting ignition behavior as a function of bulk density.

A cost-efficient method to assess carbon stocks in tropical peat soil

Abstract. Estimation of belowground carbon stocks in tropical wetland forests requires funding for laboratory analyses and suitable facilities, which are often lacking in developing nations where most tropical wetlands are found. It is therefore beneficial to develop simple analytical tools to assist belowground carbon estimation where financial and technical limitations are common. Here we use published and original data to describe soil carbon density (kgC m−3; Cd) as a function of bulk density (gC cm−3; Bd), which can be used to rapidly estimate belowground carbon storage using Bd measurements only. Predicted carbon densities and stocks are compared with those obtained from direct carbon analysis for ten peat swamp forest stands in three national parks of Indonesia. Analysis of soil carbon density and bulk density from the literature indicated a strong linear relationship (Cd = Bd × 495.14 + 5.41, R2 = 0.93, n = 151) for soils with organic C content &gt; 40%. As organic C content decreases, the relationship between Cd and Bd becomes less predictable as soil texture becomes an important determinant of Cd. The equation predicted belowground C stocks to within 0.92% to 9.57% of observed values. Average bulk density of collected peat samples was 0.127 g cm−3, which is in the upper range of previous reports for Southeast Asian peatlands. When original data were included, the revised equation Cd = Bd × 468.76 + 5.82, with R2 = 0.95 and n = 712, was slightly below the lower 95% confidence interval of the original equation, and tended to decrease Cd estimates. We recommend this last equation for a rapid estimation of soil C stocks for well-developed peat soils where C content &gt; 40%.

Correlação linear e espacial entre produtividade de Brachiaria brizantha, densidade do solo e porosidade total em função do sistema de manejo do solo

A densidade e a porosidade são propriedades físicas do solo que são alteradas em função do sistema de manejo utilizado, com consequente influência sobre a produtividade das culturas. A produtividade da planta forrageira, Brachiaria brizantha, em função da densidade do solo e da porosidade total foi analisada em dois sistemas de manejo de solo, em experimento conduzido no segundo semestre de 2009, no município de Santa Teresa, no Estado do Espírito Santo. O objetivo foi estudar a variabilidade e as correlações lineares e espaciais entre os atributos da planta e do solo, visando a selecionar um indicador da qualidade física do solo de boa representatividade para produtividade de forragem. Marcaram-se duas parcelas de 40 m por 50 m a cada 5 m, em duas direções, resultando em um reticulado retangular de 99 pontos, em cada um dos sistemas utilizados: preparo convencional e plantio direto. Os atributos estudados, além de não terem variado aleatoriamente, apresentaram variabilidade dos dados entre média e alta, e seguiram padrões espaciais bem definidos, com alcance entre 20,3 e 24,2 m. Por sua vez, a correlação linear entre o atributo da planta e os do solo, em função do elevado número de observações, foi baixa. A melhor correlação para produtividade de matéria seca foi com a densidade do solo na profundidade de 0,0 - 0,15 m, independentemente do sistema de manejo do solo, indicando que a produtividade e a densidade do solo são inversamente proporcionais. Portanto, a densidade do solo avaliada na camada de 0,0 - 0,15 m apresentou-se como satisfatório indicador da qualidade física do solo, quando se considerou a produtividade da forrageira.

Improvement of flow and bulk density of pharmaceutical powders using surface modification

Improvement in flow and bulk density, the two most important properties that determine the ease with which pharmaceutical powders can be handled, stored and processed, is done through surface modification. A limited design of experiment was conducted to establish a standardized dry coating procedure that limits the extent of powder attrition, while providing the most consistent improvement in angle of repose (AOR). The magnetically assisted impaction coating (MAIC) was considered as a model dry-coater for pharmaceutical powders; ibuprofen, acetaminophen, and ascorbic acid. Dry coated drug powders were characterized by AOR, particle size as a function of dispersion pressure, particle size distribution, conditioned bulk density (CBD), Carr index (CI), flow function coefficient (FFC), cohesion coefficient using different instruments, including a shear cell in the Freeman FT4 powder rheometer, and Hansen flowability index. Substantial improvement was observed in all the measured properties after dry coating relative to the uncoated powders, such that each powder moved from a poorer to a better flow classification and showed improved dispersion. The material intrinsic property such as cohesion, plotted as a function of particle size, gave a trend similar to those of bulk flow properties, AOR and CI. Property improvement is also illustrated in a phase map of inverse cohesion (or FFC) as a function of bulk density, which also indicated a significant positive shift due to dry coating. It is hoped that such phase maps are useful in manufacturing decisions regarding the need for dry coating, which will allow moving from wet granulation to roller compaction or to direct compression based formulations.

Complex Dielectric Properties of Microcrystalline Cellulose, Anhydrous Lactose, and α-Lactose Monohydrate Powders Using a Microwave-Based Open-Reflection Resonator Sensor

The real (ε') and imaginary (ε″) components of the complex permittivity of anhydrous lactose and microcrystalline cellulose (MCC) under different bulk densities, moisture contents (MCs), and times of hydration (for anhydrous lactose) were measured nondestructively using a microwave resonator sensor operating in the range of 700-800 MHz. Measurements of sensor resonant frequency and conductance allow, through calibration, determination of the complex dielectric properties ε' (relative permittivity) and ε″ (relative dielectric loss) of the test material. Characteristic graphs of ε″ versus ε' - 1 curve for each powder were generated as a function of bulk density and MC. Such data can be used to develop empirical models for the simultaneous in situ measurement of the bulk density and MC of the powders. Unlike MCC, anhydrous lactose is converted to its hydrate form in the presence of moisture, which causes a reduction in the amount of physisorbed and "free" water and a subsequent change in the dielectric properties. For powders such as anhydrous lactose that can form a crystal hydrate in the presence of moisture, a combination of techniques such as vibrational spectroscopy together with microwave resonator measurements are appropriate to characterize, in situ, the physical and chemical properties of the powder.

Qualidade física dos solos irrigados de algumas regiões do Brasil Central

A intensa utilização do solo com mecanização pesada e, principalmente, em condições inadequadas de umidade do solo causa, muitas vezes, a degradação de sua estrutura, resultando no aumento da sua compactação. Objetivou-se, neste trabalho, avaliar a qualidade física dos solos irrigados de algumas regiões do Brasil. O estudo foi realizado em áreas irrigadas sob pivô central, nos Estados de Goiás, GO, Minas Gerais, MG, e São Paulo, SP. Os perfis dos solos foram divididos em três camadas: superficial, intermediária e inferior e se realizaram as seguintes determinações: textura do solo, densidade do solo e de partículas e porosidade. Os solos foram agrupados em faixas de teor de argila sendo que, para cada faixa de teor de argila se estabeleceu um valor crítico de densidade do solo e de macroporosidade, acima do qual (densidade do solo) e abaixo do qual (macroporosidade), as amostras de solo foram caracterizadas com indicação de compactação. Do total de áreas amostradas na camada superficial, 14,2% das áreas do Estado de GO, 9,5% das áreas de MG e 34% das áreas de SP, apresentaram indicação de compactação do solo em função da densidade do solo e macroporosidade.

Thermodynamics and phase behavior of a triangle-well model and density-dependent variety

A hard sphere+triangle-well potential is employed to test a recently proposed thermodynamic perturbation theory (TPT) based on a coupling parameter expansion. It is found that the second-order term of the coupling parameter expansion surpasses by far that of a high temperature series expansion under a macroscopic compressibility approximation and several varieties. It is also found that the fifth-order version displays best among all of the numerically accessible versions with dissimilar truncation orders. Particularly, the superiority of the fifth-order TPT from other available liquid state theories is exhibited the most incisively when the temperature of interest obviously falls. We investigate the modification of the phase behavior of the hard sphere+triangle-well fluid resulting from a density dependence imposed on the original potential function. It is shown that (1) the density dependence induces polymorphism of fluid phase, particularly liquid-liquid transition in metastable supercooled region, and (2) along with enhanced decaying of the potential function as a function of bulk density, both the liquid-liquid transition and vapor-liquid transition tend to be situated at the domain of lower temperature, somewhat similar to a previously disclosed thumb rule that the fluid phase transition tends to metastable with respect to the fluid-solid transition as the range of the attraction part of a density-independence potential is sufficiently short compared to the range of the repulsion part of the same density-independence potential.